drm/amdgpu: Limit BO list entry count to prevent resource exhaustion

Userspace can pass an arbitrary number of BO list entries via the
bo_number field. Although the previous multiplication overflow check
prevents out-of-bounds allocation, a large number of entries could still
cause excessive memory allocation (up to potentially gigabytes) and
unnecessarily long list processing times.

Introduce a hard limit of 128k entries per BO list, which is more than
sufficient for any realistic use case (e.g., a single list containing all
buffers in a large scene). This prevents memory exhaustion attacks and
ensures predictable performance.

Return -EINVAL if the requested entry count exceeds the limit

Reviewed-by: Christian König <christian.koenig@amd.com>
Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jesse Zhang <jesse.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 688b87d39e0aa8135105b40dc167d74b5ada5332)
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
index 4662bfbe70b2d081d4e978c53a6e6707ef5a406f..43864df8af04631fab6dd2b76ee19b6f74fd8de5 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
@@ -36,6 +36,7 @@
 
 #define AMDGPU_BO_LIST_MAX_PRIORITY    32u
 #define AMDGPU_BO_LIST_NUM_BUCKETS     (AMDGPU_BO_LIST_MAX_PRIORITY + 1)
+#define AMDGPU_BO_LIST_MAX_ENTRIES     (128 * 1024)
 
 static void amdgpu_bo_list_free_rcu(struct rcu_head *rcu)
 {
@@ -188,6 +189,9 @@ int amdgpu_bo_create_list_entry_array(struct drm_amdgpu_bo_list_in *in,
        const uint32_t bo_number = in->bo_number;
        struct drm_amdgpu_bo_list_entry *info;
 
+       if (bo_number > AMDGPU_BO_LIST_MAX_ENTRIES)
+               return -EINVAL;
+
        /* copy the handle array from userspace to a kernel buffer */
        if (likely(info_size == bo_info_size)) {
                info = vmemdup_array_user(uptr, bo_number, info_size);